A servosphere device for monitoring the orientation of a freely running animal was designed and constructed. The device permits continuous alteration of sensory cues perceived by an animal and the simultaneous recording of orientation responses executed by the animal. A minicomputer controls both the recording mechanism and the electronic valves and motors that alter sensory cues. It will be possible to accurately determine the responses of animals to a changing pattern of stimuli and to probe information processing by the animal engaged in making orientation decisions.